RT Conference Proceedings
T1 Oxidation of activated carbons containing surface phosphorus functionalities
A1 Valero-Romero, María José
A1 Rodríguez-Mirasol, José
A1 Cordero-Alcántara, Tomás
K1 Carbón activado
K1 Ácido fosfórico
AB Activated carbons materials have attracted considerable attention because of their interesting application in many fields, such as catalysis, gas and liquid phase adsorption and gas and energystorage. However, the use of carbon materials in catalysis is limited since they would gasify to CO2(or CO) in the presence of oxygen at relatively low temperatures. On the other hand, it has beenshown that it is possible to prepare carbon materials with a relatively large amount of phosphoruson the carbon surface by chemical activation of lignocellulosic materials with phosphoric acid [1].This activation method leads, in certain operation conditions, to the generation of phosphorussurface complexes in form of C-O-PO3, C-PO3 and C3PO groups, which present a very high thermalstability and confer to the carbons certain surface properties of great interest in heterogeneouscatalysis applications, such as high oxidation resistance and surface acidity. The main purpose ofthe present work is to study the role of the phosphorus surface groups of these activated carbons onthe carbon surface oxidation and reduction reactions.An extensive study of the oxidation evolution of the activated carbon surface has been carried outby subjecting the carbon to thermal treatments in oxidizing and inert conditions, using differenttechniques including temperature-programmed desorption (TPD) and X-ray photoelectronspectroscopy (XPS) for the characterization of the obtained carbons. It has been proved thatphosphorus surface groups preferentially trap oxygen and are transformed from less to moreoxidizedspecies prior to carbon gasification, even at low temperature. These experimental resultsevidence the role of phosphorus surface groups on the inhibition of carbon oxidation andgasification. The high capacity of these phosphorus species to be oxidized results in activatedcarbons with a high amount of oxygen surface groups of acidic character and relatively highthermal stability.The reduction and re-oxidation of the (phosphorus) surface groups have also been proved to bereversible through successive thermal treatments in oxidizing and inert conditions. The new surfacesites generated during the reduction conditions (probably of C-PO type) may react with oxygenfrom air and regenerate the C–O–PO system, indicating the presence of redox sites on the surface ofthe activated carbon. These results open new and attractive possibilities for the use of these carbonmaterials as catalytic supports or as catalysts by themselves for reactions that take place underoxidizing conditions and at relatively high temperatures.
YR 2014
FD 2014-07-28
LK http://hdl.handle.net/10630/7938
UL http://hdl.handle.net/10630/7938
LA eng
NO Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.
DS RIUMA. Repositorio Institucional de la Universidad de Málaga
RD 20 ene 2026